This invention relates to labels for application to clothing, linens, safety belts and other like goods which are subjected to repeat cleaning and/or rough usage, and more particularly to the formation of individual washdurable labels of thermoplastic polymer fibers from a tape.
The attachment of labels to cloth goods such as clothing, linens, and other similar goods is a common practice to set forth information such as trademarks and tradenames, material identification and characteristics, care instructions, sizes and so forth. For many years, these labels were of cotton, rayon and other natural fibers. Such individual labels were usually cut from a long tape of label stock, either by the label manufacturer or the clothing manufacturer, and attached to the goods. Frequently, the cutting was performed with pinking or straight shear blades, and/or folded in various fashions and/or impregnated or coated with a binder to inhibit or limit unraveling at the ends.
In recent years, labeling requirements and other factors have necessitated use of labels made of thermoplastic fibers. Moreover, legal requirements have necessitated the use of larger and more labels as in clothing or on linens, for proper consumer protection, as well as labels that have high wash durability to remain intact and legible after many washes and much usage. Label stock formed of thermoplastic polymer fibers, either woven or nonwoven, have good general durability. But, the smooth and slippery characteristics of the fibers causing them to readily slide apart promote unraveling and concomitant disheveling of such labels at the cut ends. This has been a significant problem as is known in the trade.
In other arts where thermoplastic materials are employed, techniques such as hot wire cutting or hot blade cutting have been used. For example, film stock as for shrink wrapping or bag making has been cut with a simple hot blade arrangement. And cords or other heavy duty items like auto safety belt stock which are relatively stiff have been cut satisfactorily, although at low rates of production with a hot wire. Neither of these as known was really satisfactory for separation of thin fibrous label stock, however. This label stock varies in thickness between only about 0.004 and 0.015 of an inch, and presents very different problems from these. A hot wire is not effective on the thin flexible label type. Heated blades have been used to some extent, to sever this thin fibrous label stock, since they do form a fused smear of polymer over the ends of the severed fibers to hold them together. Unfortunately, it has been found that the holding action is not very resistant to rough usage or repeated washing or cleaning of the label with a garment. The polymer smear breaks loose from the label, allowing the fiber ends to unravel.
The present invention was discovered quite by accident, during pursuit of the development in copending application Ser. No. 436,175 filed Jan. 24, 1974. Specifically, in use of the apparatus in said application to sever label stock, it was conceived to use concentrated cooling of the platen, directly opposite the hot knife, to a temperature below that of the melting or fusion temperature of the polymer, to hopefully prevent sticking and fouling of the molten polymer on the cooled platen. The concentrated cooling accomplished this, and moreover also prevented the polymer on the label ends from sticking to other labels. So a substantial number of labels were severed with the apparatus. The heated knife not only severed the fibrous tape, but also held the fibers together by the melted polymer. created. Some time later, it was noticed with disappointment that there still was a tendency for some unraveling of the labels so formed. Further examination and evaluation showed that this tendency was primarily on one end of the individual label and not nearly so often on the other end. The present invention relates to the discovery of the problem and the solution to such problem of unraveling of thermoplastic fibers of thin labels formed from a label tape.